Valve train for a reciprocating piston internal combustion engine, and method for valve control in a reciprocating piston internal combustion engine

Abstract

A valve train for a reciprocating piston internal combustion engine may include a crankshaft, at least one inlet valve, at least one outlet valve, at least one camshaft coupled rotationally to the crankshaft, at least one inlet cam held on a first camshaft, at least one outlet cam held on one of the first camshaft or a second camshaft, at least one brake cam held on one of the first camshaft or the second camshaft, at least one inlet cam follower, which may actuate the at least one inlet valve and may be drive-connected at least at times to the inlet cam, at least one outlet cam follower, which may actuate the at least one outlet valve, may be drive-connected at least at times to the outlet cam, and, in a braking mode, may be drive-connected at least at times to the brake cam, and a phase shifting device for adjusting a phase position of the brake cam relative to the crankshaft.

The invention claimed is: 
     
       1. A valve train for a reciprocating piston internal combustion engine, the valve train comprising:
 a crankshaft; 
 at least one inlet valve and at least one outlet valve; 
 at least one camshaft coupled rotationally to the crankshaft; 
 at least one inlet cam; 
 at least one outlet cam; 
 at least one brake cam held together with the at least one outlet cam on a same one of the at least one camshaft; 
 at least one inlet cam follower, which actuates the at least one inlet valve and is drive-connected at least at times to the at least one inlet cam; 
 at least one outlet cam follower, which actuates the at least one outlet valve, is drive-connected at least at times to the at least one outlet cam, and, in a braking mode, is drive-connected at least at times to the at least one brake cam; and 
 a phase shifter for adjusting a phase position of the at least one brake cam relative to the crankshaft; 
 wherein each of the at least one camshaft has a hollow shaft and an inner shaft, which runs in the hollow shaft, the hollow shaft and the inner shaft being configured to rotate relative to one another by way of the phase shifter; 
 wherein the at least one inlet cam is held on the same one of the at least one camshaft. 
 
     
     
       2. A valve train according to  claim 1 , wherein the at least one inlet cam is held on a first camshaft of the at least one camshaft, and the at least one brake cam and the at least one outlet cam are held on a second camshaft of the at least one camshaft. 
     
     
       3. A valve train according to  claim 2 , wherein the phase shifter is configured to adjust at least one phase position of the second camshaft with respect to the crankshaft. 
     
     
       4. A valve train according to  claim 2 , further comprising a switchover apparatus that is configured to switch between a braking position and a normal position, the at least one outlet cam follower being drive-connected to the at least one brake cam in the braking position, and the at least one outlet cam follower being drive-connected to the at least one outlet cam in the normal position. 
     
     
       5. A valve train according to  claim 2 , wherein the at least one brake cam and the at least one outlet cam are arranged axially next to one another. 
     
     
       6. A valve train according to  claim 1 , wherein one of:
 the at least one inlet cam is held on the hollow shaft, and the at least one outlet cam is held together with the at least one brake cam on the inner shaft; or 
 the at least one outlet cam is held together with the at least one brake cam on the hollow shaft, and the at least one inlet cam is held on the inner shaft. 
 
     
     
       7. A valve train according to  claim 1 , further comprising a switchover apparatus that is configured to switch between a braking position and a normal position, the at least one outlet cam follower being drive-connected to the at least one brake cam in the braking position, and the at least one outlet cam follower being drive-connected to the at least one outlet cam in the normal position. 
     
     
       8. A valve train according to  claim 1 , wherein the at least one brake cam and the at least one outlet cam are arranged axially next to one another. 
     
     
       9. A method for valve control in a reciprocating piston internal combustion engine via a valve train having a crankshaft, at least one inlet valve, at least one outlet valve, at least one camshaft coupled rotationally to the crankshaft, at least one inlet cam, at least one outlet cam, at least one brake cam, at least one inlet cam follower, which actuates the at least one inlet valve and is drive-connected at least at times to the at least one inlet cam, at least one outlet cam follower, which actuates the at least one outlet valve, is drive-connected at least at times to the at least one outlet cam, and, in a braking mode, is drive-connected at least at times to the at least one brake cam, and a phase shifter for adjusting a phase position of the at least one brake cam relative to the crankshaft, the method comprising:
 drive-connecting the at least one outlet cam follower exclusively to the at least one outlet cam in a normal mode of the reciprocating piston internal combustion engine; 
 drive-connecting the at least one outlet cam follower to the at least one brake cam in the braking mode; and 
 adjusting a phase position of the at least one brake cam with respect to the crankshaft in the braking mode in order to influence a braking action; 
 wherein the at least one inlet cam, the at least one outlet cam, and the at least one brake cam are held on a same one of the at least one camshaft; and 
 wherein each of the at least one camshaft has a hollow shaft and an inner shaft, which runs in the hollow shaft, the hollow shaft and the inner shaft being configured to rotate relative to one another by way of the phase shifter. 
 
     
     
       10. A method according to  claim 9 , further comprising shifting the at least one brake cam in one of an early direction or a late direction in order to set a braking performance. 
     
     
       11. A method according to  claim 9 , further comprising:
 shifting the phase position of the at least one brake cam in a late direction in order to increase the braking action; and 
 shifting the phase position of the at least one brake cam in an early direction in order to reduce the braking action. 
 
     
     
       12. A method according to  claim 9 , wherein the phase position of the at least one brake cam with respect to the crankshaft is set independently of a phase position of the at least one inlet cam with respect to the crankshaft. 
     
     
       13. A method according to  claim 9 , wherein the phase position of the at least one brake cam with respect to the crankshaft is set independently of a phase position of the at least one outlet cam with respect to the crankshaft. 
     
     
       14. A valve train for a reciprocating piston internal combustion engine, the valve train comprising:
 a crankshaft; 
 at least one inlet valve and at least one outlet valve; 
 at least one camshaft coupled rotationally to the crankshaft; 
 at least one inlet cam held on a first camshaft of the at least one camshaft; 
 at least one outlet cam held on one of the first camshaft or a second camshaft of the at least one camshaft; 
 at least one brake cam held on one of the first camshaft or the second camshaft; 
 at least one inlet cam follower, which actuates the at least one inlet valve and is drive-connected at least at times to the at least one inlet cam; 
 at least one outlet cam follower, which actuates the at least one outlet valve, is drive-connected at least at times to the at least one outlet cam, and, in a braking mode, is drive-connected at least at times to the at least one brake cam; 
 a phase shifter for adjusting a phase position of the at least one brake cam relative to the crankshaft; and 
 a switchover apparatus that is configured to switch between a braking position and a normal position, the at least one outlet cam follower being drive-connected to the at least one brake cam in the braking position, and the at least one outlet cam follower being drive-connected to the at least one outlet cam in the normal position.